1. Field of the Invention
The present invention relates to an optical device, and more particularly, to an optical amplifying medium, a method of manufacturing the optical amplifying medium, and an optical device comprising the optical amplifying medium.
2. Description of the Related Art
When an optical signal is transmitted, an optical amplifier is used to compensate for its quality degradation caused by signal attenuation or wave distortion. The optical amplifier directly amplifies the optical signal without the need of transforming the optical signal to an electrical signal. Also, the optical amplifier can simultaneously amplify a series of wavelengths, and thus, is suitable for dense wavelength division multiplexing (DWDM).
An example of an optical amplifier is an erbium-doped optical fiber amplifier (EDFA). A conventional optical fiber amplifier includes a pumping light source for exciting erbium ions of the erbium-doped fiber (EDF) and an optical isolator for blocking a reverse progress of an optical signal. However, the EDF, that is, SiO2 doped with erbium, can be pumped only by a pumping light source that emits light having a wavelength (980 nm or 1480 nm) that can be absorbed by erbium, and such pumping light source is generally large and expensive. Thus, the conventional EDFA can hardly be miniaturized, and thus, the manufacturing costs thereof can hardly be reduced.
In order to address the problems of the conventional EDFA, a method of including Si nano-clusters, which are a sensitizer, in SiO2 doped with erbium has been disclosed. That is, SiOx (where x<2), in which erbium ion, which is an activator, and Si nano-clusters, which are a sensitizer, are included in SiO2, which is a host, is used as an amplifying medium. In this case, since the Si nano-clusters increase the efficiency of energy transfer from the host to the activator, a small light source such as a light emitting diode (LED) having a wide wavelength can be used as a pumping light source.
However, in order to form the Si nano-clusters, a high temperature annealing process is required. In a high temperature annealing, the interconnection of erbium and the Si nano-clusters can be broken and erbium ions can cluster, and thus, an optical loss can occur.